Duplex filler plug



FIG. 1 is a front perspective view of a duplex filler plug showing my new design in environmental use;

FIG. 2 is a bottom plan view thereof;

FIG. 3 is a side elevational view thereof, the opposite side being a mirror image thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is a side elevational view thereof, rotated 90° from the side elevational view shown in FIG. 3; and,

FIG. 6 is a bottom perspective view thereof.

The broken lines shown represent unclaimed subject matter and form no part of the claimed design. 

The ornamental design for a duplex filler plug, as shown and described. 